nrf52840 high voltage mode not working

RE: nrf52840 high voltage mode not working

Einar Thorsrud — Tue, 29 Apr 2025 12:03:28 GMT

Hi,

I suspect this is related to the hardware, so I have updated your private case.

RE: nrf52840 high voltage mode not working

parchment — Thu, 24 Apr 2025 19:36:11 GMT

We have also tried enabling LDO rather than DCDC in an attempt to reduce noise. This did not work. This noise is not present when powering via jtag

RE: nrf52840 high voltage mode not working

parchment — Thu, 24 Apr 2025 19:11:38 GMT

Some more info: if I remove the following line from the dts file, then the REGOUT0 voltage is 3V. However, it makes our PWM output much noisier and unusable

&reg0 {
	status = "okay";
};

RE: nrf52840 high voltage mode not working

parchment — Thu, 24 Apr 2025 13:56:25 GMT

Correction: I measure VDD to be 1.82V when powered over USB Einar Thorsrud

RE: nrf52840 high voltage mode not working

parchment — Thu, 24 Apr 2025 13:22:50 GMT

I am only able to observe MAINREGSTATUS when powering over jtag through the dev board. In this case, VDD is 3V.

When attempting to power over USB, I measure VDD to be 0V and VDDH to be 4.4V. In this case, I am unable to observe MAINREGSTATUS.

RE: nrf52840 high voltage mode not working

Einar Thorsrud — Thu, 24 Apr 2025 12:14:55 GMT

Hi,

I see. MAINREGSTATUS is set based on the hardware confiugration. So if MAINREGSTATUS is 0, that should indicate that power is provided both to VDD and VDDH pins, which puts the device in normal voltage mode. Can you confirm the states of the VDD and VDDH pins?

RE: USB Power Issue when migrating from nrf52833 to nrf52840

parchment — Wed, 23 Apr 2025 19:41:34 GMT

After some more debugging, we have narrowed down the issue. REGOUT0 is in fact being set properly. However, MAINREGSTATUS is 0 (this is when we are only powering via the jtag

RE: USB Power Issue when migrating from nrf52833 to nrf52840

parchment — Wed, 23 Apr 2025 18:54:05 GMT

Some additional info on the problem:

We are setting REGOUT0 to 3V, but we are measuring 1.8V when powering via USB or battery. Here is the function setting REGOUT0

void configure_reg0_voltage(void) {
    // Enable write access to the UICR registers
    if ((NRF_UICR->REGOUT0 & UICR_REGOUT0_VOUT_Msk) == UICR_REGOUT0_VOUT_DEFAULT) {
        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen; // Enable write mode
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {} // Wait for NVMC to be ready

        // Set the desired voltage (e.g., 3.0V)
        NRF_UICR->REGOUT0 = (UICR_REGOUT0_VOUT_3V0 << UICR_REGOUT0_VOUT_Pos);

        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren; // Enable read-only mode
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy) {} // Wait for NVMC to be ready

        // Reset for changes to take effect
        NVIC_SystemReset();
    }
}